Melena (Blood in Stool) in Dogs

23 July 23, 2015
Dr. Bari Spielman
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Overview of Melena (Bloody Stools) in Dogs

Melena, in dogs, is the presence of digested blood in the feces and makes the stools appear black and tarry. Melena is different from fresh blood in the stool (hematochezia). Melena may represent a severe, life-threatening illness, and should not be ignored. It must especially be addressed if it persists or worsens.

Melena develops when bleeding occurs into the stomach or small intestines. The bleeding must be high in the intestinal tract in order for the blood to be digested and become discolored. Bleeding into the colon or rectum (hematochezia) appears as fresh blood in the stool.

General Causes

Infectious agents

Certain drugs

Cancer

Foreign bodies in the stomach or intestines

Infiltrative and inflammatory gastrointestinal diseases

Ingestion of blood

Coagulopathies (bleeding disorders)

Metabolic and other diseases that cause gastrointestinal ulceration

Hemorrhagic gastroenteritis (HGE)

Perioperative hemorrhage (bleeding associated with surgery on the intestinal tract)

Gastrointestinal ischemia (lack of blood supply)

Ingestion of heavy metals (uncommon causes)

What to Watch For

Dark, almost black stools

Diarrhea

Vomiting

Pale gums

Other areas of bleeding or bruising on the body

Weight loss

Poor appetite

Excessive drinking or urinating

Excessive urinating

Diagnosis of Melena in Dogs

A thorough history and physical examination are often helpful in determining if melena is present and in suggesting an underlying cause. To determine the exact cause of melena in dogs, additional tests are usually necessary and include the following:

Complete blood count (CBC)

Biochemical profile

Urinalysis

Fecal examination

Abdominal and chest radiographs (X-rays)

Serology for certain infectious diseases

Coagulation profile

Abdominal ultrasonography

Upper gastrointestinal barium series

Endoscopy

Treatment of Melena in Dogs

There are several things your veterinarian might prescribe to treat your dog symptomatically while results of diagnostic tests are pending:

Individuals with melena may be treated as outpatients if there are minimal systemic signs, especially if there is a known cause that can be removed immediately.

Dietary recommendations vary depending on the cause; however, a bland diet that is easy to digest may be recommended.

Avoid all gastrointestinal irritants like corticosteroids, aspirin and other nonsteroidal anti-inflammatory drugs.

Drugs that block the production of stomach acid and coat the stomach may be recommended.

Home Care

Administer any prescribed medications and follow all dietary recommendations as directed by your veterinarian. Observe your dog’s general activity and appetite, and watch closely for the recurrence of melena, and/or presence of blood in any vomitus. Additionally, report any other signs to your veterinarian.

In-depth Information on Melena in Dogs

Melena usually indicates the presence of significant upper gastrointestinal disease, although occasionally other diseases (such as clotting disorders, ingestion of blood, etc.) unrelated to the gastrointestinal tract may present with melena. The classic appearance of melena is black, shiny, sticky, foul-smelling feces with a tarry consistency. Melena may be seen as the only clinical sign, although other systemic signs often accompany it.

Ingestion of blood must be ruled out, including swallowing blood from the oral cavity or respiratory tract, and licking blood from a wound. A careful history and thorough physical examination of these patients is essential. The presence of melena generally warrants hospitalization, extensive diagnostic testing, and supportive care. It is best to determine the underlying cause and treat the specific problem.

Causes of Melena in Dogs

There are many potential causes for melena. The most common causes are usually diseases of the gastrointestinal tract that create ulcerations or cause bleeding into the tract. Ingestion of blood or bleeding from clotting abnormalities can also cause melena. It is important to determine a cause, as specific treatment is necessary to successfully treat patients with melena.

Intestinal irritation and ulceration may occur with the administration of certain drugs, particularly corticosteroids and nonsteroidal anti-inflammatory agents (NSAIDs).

Gastrointestinal ulcerations or erosions commonly produce melena. Such ulcers may occur following acute gastric dilatation and volvulus (twisting of the stomach), heat stroke, overwhelming body infections, the overproduction of stomach acid, shock, anaphylaxis, and as a side effect of some cancers.

Gastrointestinal tumors or foreign bodies can cause bleeding and melena.

Certain metabolic diseases, such as kidney and liver failure, pancreatitis and hypoadrenocorticism (Addison’s disease) can cause bleeding into the intestinal tract.

Inflammation of the walls of the intestines (inflammatory bowel disease) can be associated with melena.

Ingested blood should be considered as a cause when bleeding is present in the oral cavity or respiratory tract, or when the animal has been witnessed licking a bleeding wound.

Hemorrhagic gastroenteritis (HGE) is a syndrome seen in dogs whose cause is unknown. It usually causes acute diarrhea with fresh blood in it, and vomiting, hematemesis (vomiting blood), and melena can also be seen.

Any time surgery is performed on the upper gastrointestinal tract, bleeding may occur into the tract. Melena can then appear 12-72 hours after surgery. This form of melena should be very transient.

Gastrointestinal ischemia (lack of blood supply) secondary to shock, volvulus (torsion), intussusception (telescoping of the bowel into itself), or infarction (blockage of circulation to an area) can cause death of the lining of the intestines and bleeding into the intestines with subsequent melena.

Heavy metal toxicity including arsenic, lead, and zinc are uncommon causes of melena in the dog.